Magnetic drain valves

ABSTRACT

A magnetic drain valve for use in conjunction with process vessels having a nonmagnetic drain line. The valve includes a tubular armature core coaxially disposed within the drain line and coupled by a stem to a drain closure cap which normally blocks the drain line. The cap is located at the bottom of the vessel, so that, when lifted, liquid from the vessel is admitted into the drain line. Surrounding the drain line is a solenoid which, when energized, produces an electromagnetic field causing the core to move upwardly, thereby raising the closure cap.

llnlted States Patent 1151 3,652,o54

Layton 1 Mar. 28, 1972 [54] MAGNETIC DRAIN VALVES Primary Examiner-Arnold Rosenthal [72] Inventor: Howard M. Layton, Ossining, N.Y. AmmeyMlchael Eben [73] Assignee: lnterlab, Inc., Pleasantville, NY. [57] ABSTRACT [22] Filed: June 1970 A magnetic drain valve for use in conjunction with process 21 Appl N 47 ,744 vessels having a nonmagnetic drain line. The valve includes a tubular armature core coaxially disposed within the drain line and coupled by a stem to a drain closure cap which normally E El/251,32 blocks the drain line The p is located a! the bonom of the 58 Field .1 seiner; 2s1/139, 65 vessel lifted quid vessel is admimd into the drain line. Surrounding the drain line is a solenoid {56] References Cited which, when energized, produces an electromagnetic field causing the core to move upwardly, thereby raising the closure UNITED STATES PATENTS cap 802,952 10/1905 Waterman ..25l/l39 3,342,384 9/1967 Jacobs ..251/139 7 Claim" 4 FOREIGN PATENTS OR APPLICATIONS 761,629 7/l95l Germany ..2Sl/l39 llllllllllllllll hui III-Ill PATENTEDMAR28 I972 12 an sls II I N VEN TOR. How/m0 7- Myrov \llllllllll lllllllllll ll MAGNETIC DRAIN VALVES BACKGROUND OF THE INVENTION This invention relates generally to solenoid-operated valves, and more particularly to a magnetic drain valve which is especially adapted for use in conjunction with wet process vessels.

Solenoid-operated valves, frequently referred to as magnetic valves, are constituted by an integral assembly of a sole noid-operated actuator and a valve body. They are commercially available with practically all types of conventional valve bodies and construction materials. Magnetic valves are usually designed for two-position operation, and may be of normallyclosed or normally-open construction.

While existing magnetically-actuated drain valves are widely used in general industrial processing installations, they have serious disadvantages when applied to micro-electronic and other similarly critical wet processing applications. The making of micro-electronic devices entails the preparation of perfectly clean metallic surfaces so that further metallic layers may be deposited on or diffused into the substrate material. Since a complex device may have to be discarded because of the failure of one element within the device, in order to obtain a high production yeild it is vital that preparatory cleaning procedures remove all dirt, grease and other foreign matter that might otherwise give rise to a defective element. Such critical cleaning steps are involved, for example, prior to etching of semiconductor substrates. If the cleaning process is carried out imperfectly, the etching will be impaired and the yield will be poorer.

The term wet process vessel, as used herein, designates a chamber into which one or more items, substrates, components, micro-circuit or semiconductor elements, or other metal or plastic pieces are introduced for the purpose of having their surfaces treated in some manner by liquid contained in or passing through the chamber.

In order to derive maximum benefit from rinsing procedures carried out in wet process vessels, it is important that the process fluid flow continuously so that contaminants flushed from the surfaces of the part being treated are immediately withdrawn from its vicinity, thereby maintaining a clean fluid zone around the part. It is essential in such vessels to prevent the build-up of regions or pockets of contaminated liquid.

One commonly-used wet process vessel takes the form of an overflow tank having a single weir at the open top thereof, such that as influent water causes the water in the tank to rise, the fluid surface is skimmed off as it spills over the weir. An advantage of this arrangement is that contaminants floating toward the fluid surface are caused to pass over the weir. However, even vessels used for flowing processes must be emptied and cleaned periodically and this dictates the use of a drain hole and some type of drain valve in conjunction therewith. When the precess vessel is in use and the drain valve is shut, the drain line or pipe which connects the drain opening of the vessel with the valve itself contains a static fluid column which communicates with the main body of flowing fluid. This condition may result in contamination of the process fluid.

A simple means of overcoming this so-called standpipe effect is to provide a closure-cap or stopper over the drain hole in the manner commonly used in domestic bathtub and washbowl installations. But this calls for a locally-operated mechanical control linkage which is impractical in many confined areas in which micro-electronic process vessels are installed. Direct operation of the drain valve is also undesirable because it is not usually accessible unless the operator reaches through a console door opening or access panel to a drain valve which is mounted directly below the vessel it serves. For this reason, an extension shaft is sometimes provided to facilitate opening and closing of the drain valves at a remote control position on the front panel of the cleaning system console.

However, in wet processing systems used in the micro-electronics industry, the typical clean-room is relatively confined,

and this dictates a compact design for processing equipment. Hence many existing designs for multi-stage work stations include relatively small consoles whose front control panels lack room for mounting the handles necessary for remote manual operation of a drain valve.

The obvious answer to this problem is to make use of a magnetic valve in the drain line. However, conventional magnetic valves are relatively bulky, and this makes it difficult to fit the valve within the limited space available in a precess system.

Also, standard valves of small size usually have small orifices which slow down the draining process. Moreover, and this is a more serious drawback, existing magnetic valves, when used for draining purposes, leave a static water column between the valve and the tank bottom, which may contaminate the cleaning liquid.

A conventional magnetic valve includes an inlet chamber which communicates with an outlet chamber through a valve seat and plug arrangement. For example, in a standard ballvalve assembly, the ball having a passage therein is seated between the inlet and outlet chambers, the ball being rotatable by means of an electromagnetic actuator, from one position in which the passage between chambers is blocked, to another in which the passage is open.

When a valve of ball or other standard type is used as a drain valve and is closed, a static water column remains in the inlet chamber. The water in this column is below the water in the vessel itself and no motion is imparted thereto by the flow forces within the vessel. Thus, exiting types of magnetic valves are not acceptable for use in conjunction with wet precess vessels wherev the presence of static liquid pockets cannot be tolerated.

SUMMARY OF THE INVENTION In view of the foregoing, it is the primary object of this invention to provide an improved magnetic valve which is highly compact, which operates efficiently and reliably, and which is particularly useful in connection with draining wet process vessels.

More specifically, it is an object of the invention to provide a magnetic drain valve which is integrated with the drain line of a wet process vessel, the operating orifice dimensions of the valve being almost equal to the of the line itself, whereby liquid may be quickly drained from the vessel.

A significant advantage of the invention is that the magnetic valve leaves no static water column in the closed state. Also, with a magnetic valve of the above-noted type, the armature assembly thereof is readily removable from the drain line to facilitate cleaning or servicing thereof.

Briefly stated, these objects are accomplished in a magnetic drain valve having an armature assembly which is received within the non-magnetic drain line of a process vessel, the assembly being constituted by a drain closure cap coupled by a stem to a tubular armature core coaxially disposed within the drain line. Surrounding the drain line is a solenoid which, when energized, creates an electromagnetic field causing the core to move upwardly and to thereby raise the closure cap to open the valve.

OUTLINE OF THE DRAWING For a better understanding of the invention, as well as other objects and further features thereof, reference is made to the following detailed description to be read in conjunction with the accompanying drawings, wherein:

FIG. 1 schematically shows a process vessel having integral therewith one preferred embodiment of a magnetic valve in accordance with the invention;

FIG. 2 is a longitudinal section taken through the magnetic valve shown in FIG. 1;

FIG. 3 is a perspective view which is cutaway to expose the interior of another embodiment of magnetic valve in accordance with the invention; and

FIG. 4 is a longitudinal section taken through the valve shown in FIG. 3.

DESCRIPTION OF THE INVENTION Referring now to FIG. 1, there is illustrated a conventional wet process vessel having an inlet 11 communicating with the bottom 10A of the vessel, and an overflow outlet 12. The vessel is supported below the counter 13 of a work station, and in operation, is filled with liquid which serves to clean or otherwise treat workpieces suspended therein. The nature and operation of the wet process vessel forms no part of the present invention, which is applicable to any drain line formed of non-magnetic material. The particular process vessel shown is solely by way of example, the invention being adaptable to any pipe or line formed of non-magnetic material.

Process vessel 10 is provided with a drain line 14 which communicates with the bottom 10A of the vessel, the junction thereof having a circular depression or well 10B, as best seen in FIG. 2. Drain line 14 is formed of non-magnetic material which may be of plastic or any suitable metal. Received within line 14 is an armature assembly constituted by a closure cap 15, a hollow cylindrical stem 16 of non-magnetic material, having an upper section 16A and a lower section 16B, and a ferromagnetic tubular armature core 17, preferably formed of soft iron. Core 17 is threadably joined to the upper and lower sections of the stem to provide a drain passage therethrough.

Closure cap is dimensioned to fit within well 108 of the process vessel, and to lie flush with the bottom 10A. Cap 15 is provided with an O-ring 18 which is accommodated within an annular groove 15A to effect a liquid-tight seal when the valve is closed. The stem and armature sub-assembly 16A 17 16B is disposed coaxially within drain line 14, the internal diameter thereof being somewhat smaller than that of the line but sufficiently large to afford a relatively large valve orifice. Upper section 16A of the stem, which is joined to cap 15, is provided with a circumferential array of slots 19 to admit liquid into the tubular stem when the cap is lifted above well 108.

Encircling drain pipe 14 is a solenoid 20 which, when energized by a voltage applied to terminals 21, creates an electromagnetic field that penetrates the non-magnetic drain pipe 14 and influences core 17 to cause the core to assume a position in registration with the solenoid. The solenoid by secured to drain pipe 14 by upper and lower clamps 22 and 23. By releasing the clamp screws, one may slide solenoid 20 up or down the drain pipe, as desired.

The position of solenoid 20 is such that when core 17 is drawn upwardly within the drain pipe into registration with the solenoid, cap 15 is lifted above well 108 to open the valve, as shown in FIG. 2. But when the solenoid is deenergized, the weight of the armature assembly is such as to cause it to drop within the drain line to close and seal the valve. The position of the solenoid on the drain pipe is not critical.

While the weight of the armature assembly maintains the closed position of the valve, an alternative approach is to use a polarized core made of non-magnetic material and to apply a direct voltage to the solenoid which in one polarity raises the core and in another urges the core downwardly to provide a closure force on the cap.

In practice, solenoid 20 may be formed of two arcuate sections connected in series, adapted to be clamped about the drain line to facilitate its installation. The core 17 is preferably coated with a material which is non-reactive with the cleaning liquid, and for this purpose, the core may be clad with stainless steel or a plastic skin.

Because of the absence of a mechanical linkage, the armature assembly may be readily lifted from the drain line for cleaning or servicing purposes, the drain line then being unencumbered by any fittings or obstructions.

It is important to note that when the valve is closed, the cap is flush with the bottom of the vessel, and there is no static water column between the bottom of the process vessel and the valve. Consequently, there are no stand-pipe effects leading to contamination of is process vessel bath.

The embodiment shown in FIGS. 3 and 4 functions in the same manner as that in FIGS. 1 and 2 except that the osition of the armature core on the stem is longitudinally a ustable within a broad range so as to permit the solenoid to be placed at any desired level below the drain orifice. For this purpose, the armature assembly includes a threaded rod-like stem 24 which is centrally attached to the underside of closure cap 15, and is provided with a spider 25 serving as a spacer guide within the drain line.

Threadably received on stem 24 is an adjustable gravity weight 26 having an array of struts 27 adapted to support a tubular armature core 28 concentrically with respect to the stem. Thus, by rotating the weight on the stem, the core may be raised or lowered with respect to solenoid 20 to assume a position therein appropriate to the solenoid position.

While there have been shown and described preferred embodiments of magnetic drain valves in accordance with the invention, it will be appreciated that many changes and modifications may be made therein without, however, departing form the essential spirit of the invention.

I claim:

1. A magnetic drain valve for a non-magnetic drain line communicating with the bottom of a wet process vessel, said valve comprising:

A. a removable armature assembly receivable within said line and constituted by a closure cap, a tubular armature core coaxially disposed in the line, and a stem interconnecting the core and the cap, said stem being in the form of a threaded rod having a gravity-weight threadably supported therein, said tubular core being mounted on said weight whereby the longitudinal position of said core may be adjusted by rotation of said weight, and

B. an electrically energizable solenoid surrounding the line at a position creating a magnetic field which penetrates the line and influences the core to cause it to shift upwardly within the line, thereby raising the cap to open the valve.

2. A valve as set forth in claim 1, wherein said core is fabricated of ferromagnetic material.

3. A valve as set forth in claim 1, wherein said core is a permanent magnet.

4. A valve as set forth in claim 1, wherein said process vessel is provided with a depressed well at the junction of the drain line and the bottom of the vessel, said cap in the closed position of the valve being seated within the well to be flush with said bottom.

5. A valve as set forth in claim 4, wherein the underside of said cap is provided with an O-ring to afford a liquid seal.

6. A valve as set forth in claim 1, wherein said stem is provided with a spider forming a spacer guide.

7. A valve as set forth in claim 1, wherein said core is protectively coated with a material non-reactive with the process liquid.

UNTTED STATES PATENT ()FFICE I CERTIFICATE OF I CORRECTTON Pat nt No 3,652,054 Dated March 28.1Q77

Inventofls) Howard M.- Layton It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 9, "preoess" should have read process line 28, "exiting" hould have read existing line 43, "the of" should read F i that of Column 3, line 41, "by" should have read is line 54, "non-magnetic" should have been v permanent-magnet Colurm 4 line 9, "is" should have read the Signed and sealed this 22nd day of August 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting; Officer Commissioner of Patents FORM PO-1050 (10-69) USCQMNMDC 60375-p6g a us. GOVERNMENT PRINTING OFFICE: I969 0-366-384 

1. A magnetic drain valve for a non-magnetic drain line communicating with the bottom of a wet process vessel, said valve comprising: A. a removable armature assembly receivable within said line and constituted by a closure cap, a tubular armature core coaxially disposed in the line, and a stem interconnecting the core and the cap, said stem being in the form of a threaded rod having a gravity-weight threadably supported therein, said tubular core being mounted on said weight whereby the longitudinal position of said core may be adjusted by rotation of said weight, and B. an electrically-energizable solenoid surrounding the line at a position creating a magnetic field which penetrates the line and influences the core to cause it to shift upwardly within the line, thereby raising the cap to open the valve.
 2. A valve as set forth in claim 1, wherein said core is fabricated of ferromagnetic material.
 3. A valve as set forth in claim 1, wherein said core is a permanent magnet.
 4. A valve as set forth in claim 1, wherein said process vessel is provided with a depressed well at the junction of the drain line and the bottom of the vessel, said cap in the closed position of the valve being seated within the well to be flush with said bottom.
 5. A valve as set forth in claim 4, wherein the underside of said cap is provided with an O-ring to afford a liquid seal.
 6. A valve as set forth in claim 1, wherein said stem is provided with a spider forming a spacer guide.
 7. A valve as set forth in claim 1, wherein said core is protectively coated with a material non-reactive with the process liquid. 